Sonex series pickups, coil tap and controls

1980 Gibson Sonex owners manual - page 7

The Sonex Deluxe was equipped with "high output" Sonex Deluxe humbuckers, part numbers 13248 and 13249 (neck and bridge respectively) whilst the Standard and Custom both had a pair of "extremely high output" Gibson "Dirty Fingers" humbuckers (parts 13238 and 13239). The Standard and Custom were also fitted with coil tap circuitry, allowing the pickups to act either as humbuckers, or single coils..

...a coil tap switch, which in the "up" position has no function and allows full humbucking capabilities. In the "down" position, one coil in each of the humbucking pickups is bypassed (the ones closest to each other or "inside" coils) leaving just one coil in each pickup active(the "outside" coils) producing a true single coil pickup sound